This study investigates the dynamic behavior of braided pneumatic actuators (BPAs) under bio-inspired pulse modulation control to enhance their biomimetic performance. Building upon prior research on pulse timing and force amplification, we develop a state-space model to characterize the relationship between valve actuation and system pressure, optimized using Particle Swarm Optimization (PSO). A nonlinear model is then used to correlate pressure with force output via trust-region reflective least squares. Experiments were conducted on Festo BPAs at fixed lengths of 600 mm, 310 mm, and 140 mm, across various pulse frequencies and durations. Results show that the PSO-optimized model accurately predicts pressure behavior, with average errors of 5–16% depending on muscle length. The pressure-to-force model yielded errors below 3%, effectively capturing the nonlinear force response. Our findings reveal that shorter BPAs respond more quickly but require higher pulse frequencies to maintain force, while longer BPAs exhibit higher peak forces and slower deflation, enabling smoother force output. These insights contribute to the development of more adaptable and efficient soft robotic systems.